Shows how to replace the pre-catylitic converter oxygen sensor. This is an easy install you can do yourself. BMW rates oxygen sensors to 100,000 miles but they often can last a lot longer. But for better fuel economy it is recommended to replace them at 100,000 miles on your BMW E46, E38, E39 with the M54 engine. Some common fault codes involved with a failure are P1189, P1188, P0155